Methods and Apparatus for RF Handoff in a Multi-Frequency Network

ABSTRACT

Methods and apparatus for RF handoff in a multi-frequency network. In an aspect, a method includes generating a content preserving handoff table that includes a current LOI and neighboring LOIs carrying at least the same wide and local content multiplexes as the current LOI, and determining that handoff conditions are met for a content preserving handoff, selecting a selected LOI from the content preserving handoff table and a selected RF channel associated with the selected LOI, and performing a handoff to the selected RF channel in the selected LOI if the selected LOI is different than the current LOI. An apparatus includes means for generating a content preserving handoff table, means for determining that handoff conditions are met for a content preserving handoff, means for selecting a selected LOI and a selected RF channel, and means for performing a handoff to the selected RF channel in the selected LOI.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present application for patent is a Continuation-in-Part and claimspriority to patent application Ser. No. 12/051,758, entitled “Methodsand Apparatus for RF Handoff in a Multi-Frequency Network”, filed Mar.19, 2008, pending, and claims priority to Provisional Application No.60/896,255 entitled “Methods and Apparatus for Providing Handoff inMultiple Frequency Networks” filed Mar. 21, 2007, and to ProvisionalApplication No. 60/945,292, entitled “Methods and Apparatus forProviding Handoff in a Multiple Frequency Network,” filed Jun. 20, 2007,both assigned to the assignee hereof and hereby expressly incorporatedby reference herein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to Provisional Application No. 60/910,191,entitled “Methods and Apparatus for Providing Flow Data AcquisitionPriority Scheme in a Multiple Frequency Network,” filed Apr. 4, 2007,and to Provisional Application No. 60/945,317, entitled “Methods AndApparatus for Providing Flow Data Acquisition Priority Scheme in aMultiple Frequency Network,” filed Jun. 20, 2007, both assigned to theassignee hereof and hereby expressly incorporated by reference herein.

BACKGROUND

1. Field

The present application relates generally to the operation of datanetworks, and more particularly, to methods and apparatus for RF channelselection in a multi-frequency network.

2. Background

Data networks, such as wireless communication networks, have to tradeoff between services customized for a single terminal and servicesprovided to a large number of terminals. For example, the distributionof multimedia content to a large number of resource limited portabledevices (subscribers) is a complicated problem. Therefore, it isimportant for network operators, content retailers, and serviceproviders to have a way to distribute content and/or other networkservices in a fast and efficient manner and in such a way as to increasebandwidth utilization and power efficiency. A multi-frequency network(MFN) is a network in which multiple radio frequencies (RFs) (or RFchannels) are used to transmit media content. One type of MFN is ahorizontal multi-frequency network (HMFN) where a distribution waveformis transmitted over different RF channels in different local areas. Thesame or different content may be transmitted as part of distributionwaveform carried over different RF channels in such local areas. Anothertype of MFN is a vertical multi-frequency network (MFN) in whichmultiple radio frequency (RF) channels are used in a given local area totransmit independent distribution waveforms with an aim to increase thecapacity of the network (in terms of the ability to deliver more contentto a device/end user). An MFN deployment may also consist of VMFN incertain areas and HMFN in certain other areas.

In a typical HMFN, a local operations infrastructure (LOI) comprisestransmitting sites that operate to transmit a single distributionwaveform over an RF channel in a selected geographic area. In a typicalVMFN, a local operations infrastructure (LOI) comprises transmittingsites that operate to transmit multiple distribution waveforms overmultiple RF channels in a selected geographic area. Each distributionwaveform may comprise one or more content flows that can be selected ata receiving device for rendering. Adjacent LOIs may utilize the same ordifferent RF channels.

During operation, a receiving device may perform an RF handoff as aresult of data acquisition failures for desired content. For example,acquisition failures can happen due to varying channel conditions as aresult of device mobility. Typically, the device may handoff to anyavailable RF channel that carries the desired content. However, if thedevice randomly hands off to any RF channel that carries the desiredcontent, the LOI associated with the selected RF channel may not carryother content that is in common with the current LOI. Also, the LOIassociated with the selected RF channel may not carry any additionalcontent that is not available in the current LOI. For example, the LOIassociated with the selected RF channel may carry less common content(with the current LOI) than LOIs associated with other available RFchannels carrying the desired content. This situation may result in thedevice not having access to common and additional content after an RFhandoff, which will adversely impact the user experience.

Therefore, it is desirable to have a handoff mechanism that operates toallow a device to perform a handoff in a multi-frequency network in afast and efficient manner and to maximize common and additional contentfor an enhanced user experience.

SUMMARY

In one or more aspects, a handoff system, comprising methods andapparatus, is provided that operates to provide handoff in amulti-frequency network. For example, when a handoff event is detected,the handoff system determines a new RF channel to which a device maytune to receive desired content. The handoff system operates to considera plurality of factors, including but not limited to, signal strength,content availability, and other factors to determine the new RF channel.After the switch to the new RF channel, the device can receive thedesired content and has the ability to switch to additional content thatmay be available on other RF channels in the associated LOI in a fastand efficient manner.

In an aspect, a method is provided for RF channel handoff in amulti-frequency network. The method comprises generating a contentpreserving handoff table, wherein the content preserving handoff tablecomprises a current LOI and neighboring LOIs carrying at least the samewide and local content multiplexes as the current LOI, and determiningthat handoff conditions are met for a content preserving handoff. Themethod also comprises selecting a selected LOI from the contentpreserving handoff table and a selected RF channel associated with theselected LOI, and performing a handoff to the selected RF channel in theselected LOI if the selected LOI is different than the current LOI.

In an aspect, an apparatus is provided for RF channel handoff in amulti-frequency network. The apparatus comprises processing logicconfigured to generate a content preserving handoff table, wherein thecontent preserving handoff table comprises a current LOI and neighboringLOIs carrying at least the same wide and local content multiplexes asthe current LOI, determine that handoff conditions are met for a contentpreserving handoff, and select a selected LOI from the contentpreserving handoff table and a selected RF channel associated with theselected LOI. The apparatus also comprises channel switch logicconfigured to perform a handoff to the selected RF channel in theselected LOI if the selected LOI is different than the current LOI.

In an aspect, an apparatus is provided for RF channel handoff in amulti-frequency network. The apparatus comprises means for generating acontent preserving handoff table, wherein the content preserving handofftable comprises a current LOI and neighboring LOIs carrying at least thesame wide and local content multiplexes as the current LOI, and meansfor determining that handoff conditions are met for a content preservinghandoff. The apparatus also comprises means for selecting a selected LOIfrom the content preserving handoff table and a selected RF channelassociated with the selected LOI, and means for performing a handoff tothe selected RF channel in the selected LOI if the selected LOI isdifferent than the current LOI.

In an aspect, a computer program product is provided for RF channelhandoff in a multi-frequency network. The computer program productcomprises a machine-readable medium that comprises a first set of codesfor causing a computer to generate a content preserving handoff table,wherein the content preserving handoff table comprises a current LOI andneighboring LOIs carrying at least the same wide and local contentmultiplexes as the current LOI, and a second set of codes for causing acomputer to determine that handoff conditions are met for a contentpreserving handoff. The machine readable medium also comprises a thirdset of codes for causing a computer to select a selected LOI from thecontent preserving handoff table and a selected RF channel associatedwith the selected LOI, and a fourth set of codes for causing a computerto perform a handoff to the selected RF channel in the selected LOI ifthe selected LOI is different than the current LOI.

In an aspect, at least one integrated circuit is provided that isconfigured for RF channel handoff in a multi-frequency network. The atleast one integrated circuit comprises a first module configured togenerate a content preserving handoff table, wherein the contentpreserving handoff table comprises a current LOI and neighboring LOIscarrying at least the same wide and local content multiplexes as thecurrent LOI, and a second module configured to determine that handoffconditions are met for a content preserving handoff. The at least oneintegrated circuit also comprises a third module configured to select aselected LOI from the content preserving handoff table and a selected RFchannel associated with the selected LOI, and a fourth module configuredto perform a handoff to the selected RF channel in the selected LOI ifthe selected LOI is different than the current LOI.

Other aspects will become apparent after review of the hereinafter setforth Brief Description of the Drawings, Description, and the Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects described herein will become more readily apparentby reference to the following Description when taken in conjunction withthe accompanying drawings wherein:

FIG. 1 shows a network that illustrates the operation of aspects of ahandoff system for use in multi-frequency network;

FIG. 2 shows a transmission frame and neighbor description informationfor use in aspects of a handoff system;

FIG. 3 shows RF channel selection logic for use in aspects of aselection system;

FIG. 4 shows an exemplary seamless handoff table applicable for use as awide or local seamless handoff table in aspects of a handoff system;

FIG. 5 shows an exemplary seamless handoff table applicable for use as awide+local seamless handoff in aspects of a handoff system;

FIG. 6 shows an exemplary partially seamless handoff table applicablefor use as a wide, local, or wide+local partially seamless handoff tablein aspects of a handoff system;

FIG. 7 shows a method for performing a handoff for use in aspects of ahandoff system;

FIG. 8 shows a method for performing a handoff procedure for use inaspects of a handoff system;

FIG. 9 shows a method for providing a handoff event trigger foractivated flows for use in aspects of a handoff system;

FIG. 10 shows a method for providing a handoff event trigger foractivated flows for use in aspects of a handoff system;

FIG. 11 shows a method for providing a handoff event trigger forregistered flows for use in aspects of a handoff system;

FIG. 12 shows a method for providing a handoff event trigger forregistered flows for use in aspects of a handoff system;

FIG. 13 shows examples of seamless handoff tables for use in aspects ofa handoff system;

FIG. 14 shows examples of partially seamless handoff tables for use inaspects of a handoff system;

FIG. 15 shows RF handoff logic for use in aspects of a handoff system;

FIG. 16 shows an exemplary content preserving handoff table applicablefor use in aspects of a handoff system;

FIG. 17 shows an exemplary method for providing a content preservinghandoff for use in aspects of a handoff system; and

FIG. 18 shows handoff logic for use in aspects of a handoff system.

DESCRIPTION

In one or more aspects, a handoff system is provided that operates at adevice to determine an RF channel in a multi-frequency network to whicha handoff may be performed so that desired content can be received. Inan aspect, the handoff system assembles information related toneighboring RF channels and the content they carry. This information isassembled into seamless and partially seamless handoff tables. A handoffevent is initiated when data acquisition fails for desired content. Whena handoff event is detected, the handoff system operates to process thegenerated handoff tables to determine a new RF channel to which thedevice can switch to receive desired content.

The system is well suited for use in wireless network environments, butmay be used in any type of network environment, including but notlimited to, communication networks, public networks, such as theInternet, private networks, such as virtual private networks (VPN),local area networks, wide area networks, long haul networks, or anyother type of data network.

DEFINITIONS

The following definitions are used herein to describe aspects of aselection system.

-   1 Local Area—Refers to a local geographic area such as a building,    group of buildings, community, city, county or other local region in    which services may be broadcast.-   2. Wide Area—Refers to a wide geographic area such as a county,    state, multiple states, country, multiple countries or other wide    region in which services may be broadcast.-   3. Multiplex—Refers to a grouping of content flows.-   4. Wide Area Multiplex—Refers to a grouping of content flows that    are broadcasted over at least one wide area.-   5. Local Area Multiplex—Refers to grouping of content flows that are    broadcasted over at least one local area.-   6. Wide Area Operations Infrastructure (WOI)—Refers to a grouping of    transmitters and associated systems that operate to transmit content    flows over a wide area. A WOI maps to the smallest geographical wide    area which can carry a wide area multiplex. A wide area multiplex    may be broadcasted over one or more WOs.-   7. Local Area Operations Infrastructure (LOI)—Refers to a grouping    of transmitters and associated systems that operate to transmit    content flows over a local area. A LOI maps to the smallest    geographical local area which can carry a local area multiplex. A    local area multiplex may be broadcasted over one or more LOs.-   8. RF Channel—Refers to an RF frequency that is used to convey a    content distribution waveform over a selected LOI.

9. Content Channel—Refers to selected content flows within a particulardistribution waveform. For example, a distribution waveform may comprisemultiple content channels and each content channel may comprise one ormore content flows.

Acronyms

The following acronyms are used herein to describe aspects of aselection system.

LM—Local Area Multiplex WM—Wide Area Multiplex NOC—Network OperationsCenter WOI—Wide Area Operations Infrastructure LOI—Local Area OperationsInfrastructure NDM—Neighbor Description Message WID—Wide AreaDescrambling Identifier LID—Local Area Descrambling IdentifierOIS—Overhead Information Symbols CC—Control Channel

FIG. 1 shows a network 100 that illustrates the operation of aspects ofa handoff system to provide RF channel selection in multi-frequencynetwork. For example, the network 100 comprises four WOIs (WOI1, WOI2,WOI3, and WOI4) each comprising one LOI (LOI1, LOI2, LOI3, and LOI4,respectively) of a multi-frequency network. Within each LOI, one or moreRF channels are used to transmit content. LOI2 and LOI3 have a verticalMFN with two RF channels in each of these LOIs. LOI1 and LOI4 carry onlyone RF channel. Each RF channel has an associated WID/LID thatidentifies descrambling sequences that can be used to descramble contenttransmitted on that RF channel. LOI1, LOI2, LOI3, and LOI4 areneighboring LOIs as shown in the network 100. The LOI1 has LOI2 as itsneighbor, the LOI2 has LOI1, LOI3 and LOI4 as its neighbors, the LOI3has LOI2 as its neighbor and LOI4 has LOI2 as its neighbor.

The network 100 comprises a network operations center (NOC) 102 thatoperates to receive wide and local content multiplexes for distributionover selected wide and local areas of a multi-frequency network. The NOC102 also operates to configure the multi-frequency network to distributethat content. To accomplish this, the NOC 102 is aware of the geographicregions of the network that are covered by the LOIs, the RF channelsused in each region, and any other network information that may beneeded to configure the network and distribute the wide and local areacontent multiplexes. It should be noted that the network 100 maycomprise any number of LOIs.

In an aspect, the NOC 102 comprises neighbor description logic 104. Theneighbor description logic 104 operates to assemble information relatingto the list of neighboring LOIs for each LOI and the WID/LIDdescrambling identifiers that are associated with the RF channels ineach LOI. For example, the wide and local area content multiplexes arescrambled with wide area and local area scrambling sequences beforetransmission over the network 100. In an aspect, the neighbordescription logic 104 operates to generate neighbor description messages(NDMs) that are configured to provide a list of neighboring LOIsassociated with a particular LOI and WID/LID identifiers that identifydescrambling sequences associated with RF channels of the particular LOIand its neighboring LOs. In another aspect, the NDM messages areconfigured to provide a list of neighboring LOIs and WID/LID identifiersassociated with RF channels for any selected group of LOs. A moredetailed description of the NDM messages generated by the neighbordescription logic 104 is provided in another section of this document.

The NOC 102 operates to transmit the wide and local area multiplexes andthe generated NDMs to the LOIs in the network 100. It should be notedthat although only four LOIs are shown, the NOC 102 may transmit themultiplexes and associated NDMs to any number of LOs.

In an aspect, the LOI1, LOI2, LOI3, and LOI4 comprise one or moretransmitter sites. For example, the LOI1 comprises transmitter site 106.Each transmitter site operates to transmit a distribution waveform on aselected RF channel over its respective LOI. It should be noted thateach transmitter site comprises one or more servers as illustrated at108.

In an aspect, the NOC 102 operates to transmit the content multiplexesand the NDMs to the transmitter sites using any suitable transportmechanism. For example, the content multiplexes and the NDMs aretransmitted to servers associated with each transmitter site, asillustrated at 110. In an aspect, the NOC 102 transmits the contentmultiplexes and the NDM messages to the transmitter sites using anMPEG-2 transport mechanism. In this configuration, the multiplexes andNDM messages are assigned MPEG-2 transport identifiers so that serversat each transmitter site can detect and receive selected contentmultiplexes and an NDM message which are directed to them, respectively.

The servers at the transmitter sites use the transport identifiers todetermine which multiplexes and NDM message are intended for them todistribute over their respective LOs. The servers then operate to packtheir respective multiplexes and the NDM message into transmissionframes for transmission over selected RF channels. The servers utilizeany suitable physical layer process to pack the multiplexes and the NDMmessage into the transmission frames for transmission. By using thetransport identifiers to determine the multiplexes and the NDM messageintended for transmission over their respective LOs, the servers at thetransmitter sites need not decode any of the multiplexes or NDMmessages. The servers simply detect the appropriate transportidentifiers and then pack the identified multiplexes and the NDM messageinto the transmission frames according to the physical layer process.

The transmission frames comprise content flows associated with the wideand local area multiplexes and the NDM message generated by the neighbordescription logic 104. In an aspect, the transmission frames comprisewide and local data partitions that are used to convey the wide andlocal area content flows, respectively. In addition, the wide and localpartitions comprise wide and local control channels. In an aspect, thelocal control channel is used to distribute the NDM message generated bythe neighbor description logic 104 to the devices in each LOI.

In an aspect, the transmitter sites transmit transmission frames overtheir respective LOIs using the designated RF channels. By usingmultiple RF channels in LOIs for transmitting transmission frames, thenetwork 100 is able to transmit more content flows over such LOs. Itshould be noted that the transmitter sites within a LOI may beco-located or separated by any desired distance. It should also be notedthat the NDMs distributed over each LOI may be different because eachLOI may have a different set of neighbor LOIs and each neighbor LOI maybe associated with different RF channels and associated descramblingsequences with which to descramble the transmitted content.

Within each LOI, descrambling sequence identifiers are associated witheach RF channel. The descrambling sequence identifiers comprise widearea descrambling sequence identifiers (WID) and local area descramblingsequence identifiers (LID). The descrambling sequence identifiersidentify descrambling sequences that can be used to descramble contentreceived in a particular LOI on a particular RF channel. Thedescrambling sequence identifiers also identify content multiplexescarried on a particular RF channel. For example, in LOI2 there are twoRF channels (i.e., RF2, RF3) and each RF channel is associated withdescrambling sequence identifiers that identify descrambling sequencesthat can be used to descramble associated wide area and local areacontent multiplexes. For example, RF2 is associated with WID1 and LID1and carries wide multiplex WM1 and local multiplex LM1; and RF3 isassociated with WID2 and LID2 and carries wide multiplex WM2 and localmultiplex LM2. WID1, LID1, WID2 and LID2 identify multiplexes WM1, LM1,WM2 and LM2 respectively.

A device 112 operating in the LOI2 is tuned to receive wide area contenton channel RF2 that can be descrambled with a descrambling sequenceidentified by WID1. Details of the device 112 are shown at 114. Thedevice 112 comprises a receiver 116 that operates to tune to a selectedRF channel to receive transmission frames. For example, the receiver 116is tuned to RF2 in LOI2 to receive transmission frames. The transmissionframes that are received comprise a local control channel that conveysneighbor description information in one or more NDMs. For example, theNDMs are generated by the neighbor description logic 104 and distributedto the LOIs shown in FIG. 1. In an aspect, an NDM comprises the list ofneighboring LOIs for a device's current LOI (i.e. LOI2 for device 112)and WID/LID descrambling identifiers that identify descramblingsequences that are associated with RF channels in the current LOI (i.e.,LOI2) and its neighboring LOIs (i.e., LOI1, LOI3 and LOI4). The receiver116 passes the neighbor description information received in an NDM (orthe NDM itself) to RF handoff logic 118, as illustrated at 122. Thereceiver 116 also descrambles the received content using the correctWID/LID identifiers associated with RF2 in LOI2 and passes thedescrambled content to a decoder 120 that operates to render the contentfor the device user.

The RF handoff logic 118 operates to receive the NDM at 122. The NDMspecifies a list of neighboring LOIs for a given LOI and WID/LIDidentifiers for RF channels in the given LOI and its neighboring LOs.From this information, the RF handoff logic 118 operates to generateseamless handoff tables and partially seamless handoff tables forcontent multiplexes carried in device's current LOI. The seamless andpartially seamless handoff tables for a given content multiplex carriedin the current LOI provide a list of neighboring RFs which can beswitched to acquire the given content multiplex. The seamless andpartially seamless handoff tables are computed separately for wide andlocal content multiplexes. For example, a neighboring RF channel has anentry in the wide seamless handoff table associated with a given widecontent multiplex carried in the current LOI if that neighboring RFchannel carries the given wide content multiplex and if the LOIassociated with the neighboring RF channel carries the same set or asuperset of wide content multiplexes as the device's current LOI. Aneighboring RF channel has an entry in the wide partially seamlesshandoff table associated with a given wide content multiplex carried inthe current LOI if that neighboring RF channel carries the given widecontent multiplex and if the LOI associated with the neighboring RFchannel does not carry the same set or a superset of wide contentmultiplexes as the device's current LOI.

In an aspect, an RF handoff may be desired due to one or more handoffevents. A handoff event causes the handoff logic 118 to determine a newRF channel and to send a request 124 to the receiver 116 to tune to thenew RF channel. The handoff events are events that cause the device 112to switch from one RF channel to another RF channel to receive a desiredcontent flow. In an aspect, a handoff event can be triggered by or beperformed as a result of content acquisition failures associated withdesired content (e.g. failures due to varying channel conditions becauseof device mobility).

In an aspect, content acquisition failures associated with devicemobility occur when the device 112 moves from a region covered by LOI2to a region covered by one or more neighboring LOs. For example, thedevice receiver 116 is tuned to receive a desired content flow on aparticular RF channel in LOI2. The RF handoff logic 118 operates todetermine an RF channel in a neighboring LOI that the receiver 116 cantune to in order to continue to receive the desired content flow when acontent acquisition failure is detected as the device 112 moves outsidethe coverage area of LOI2.

To determine a new RF channel carrying the desired content flow, the RFhandoff logic 118 operates to perform one or more of the followingfunctions in aspects of the handoff system.

-   1. Determine (from received neighbor description information) a list    of available RF channels in neighboring LOIs that carry the desired    content flow so that a smooth transition can be performed from the    content acquisition perspective.-   2. Monitor signal strength of neighboring RF channels.-   3. Generate seamless and partially seamless handoff tables for    desired content. These tables comprise entries based on the list of    available RF channels and the content available in LOIs associated    with these RF channels.-   4. Rank the RF channels within the seamless and partially seamless    tables.-   5. Select a selected RF channel from the seamless handoff table    based on rank, wherein the selected RF channel meets RF selection    criteria.-   6. Select the selected RF channel from the partially seamless    handoff table based on rank wherein the selected RF channel meets RF    selection criteria, if selection from the seamless handoff table    fails.

Once the RF channel is determined, the RF handoff logic 118 outputs anRF channel switch message 124 to the receiver 116 to implement the RFhandoff. The RF channel switch message contains the correct WID/LIDidentifiers for the selected RF channel so that the desired content flowcan be descrambled by the receiver 116. The receiver 116 performs an RFchannel switch to the selected RF channel and descrambles content usingthe WID/LID received in the channel switch message.

Therefore, in various aspects, the handoff system operates to determinewhich of the available RF channels in a multi-frequency network is to beselected for handoff so that the reception of desired content cancontinue after content acquisition failures are detected for the desiredcontent. The handoff system determined the selected RF channel based onseamless and partially seamless handoff tables that are used to rank theavailable RF channels. Thus, the handoff system operations to select anavailable RF channel with the highest ranking which meets RF selectioncriteria. The RF selection criteria ensure that the selected RF channelhas a large enough received signal strength indicator (RSSI) value andalso meets RF handoff criteria. Details of RF handoff criteria areprovided in other sections of this document.

FIG. 2 shows a diagram of a transmission frame 200 for use in aspects ofa handoff system. For example, the transmission frame 200 may be packedwith wide and local content multiplexes and transmitted over the RFchannels in the LOIs shown in FIG. 1.

The transmission frame 200 comprises four sub-frames, shown generally at202, that are used to convey wide and local content. For example, eachsub-frame 202 comprises a wide area partition 204 that is packed withwide area content, and a local area partition 206 that is packed withlocal area content.

Included in the wide area partition 204 is a wide area control channel208. The wide area control channel 208 operates to convey messagespertaining to wide area content multiplexes. Included in the local areapartition 206 is a local area control channel 210. The local areacontrol channel 210 operates to convey messages pertaining to local areacontent multiplexes. In an aspect, the local area control channel isused to convey neighbor description information as part of the NDMmessage for use in aspects of a handoff system.

At the start of the transmission frame 200 are overhead informationsymbols (OIS) 212 that provide overhead information that is used tolocate the wide area control channel, the local area control channel,and the wide and local content that is packed into the sub-frames 202.The OIS 212 comprises wide overhead information symbols (WOIS) and localoverhead information symbols (LOIS).

In an aspect, content flows are transmitted using Media Logical Channels(MLCs) inside the sub-frames 202. A single MLC may be used to carry oneor more content flows. Content flow data can be successfully acquiredeven if all packets in an MLC are not received correctly because ofredundancy added in the data transmitted as part of the MLC. Dataacquisition fails for a content flow if MLC packet erasures exceed theallowed error threshold based on added redundancy in the datatransmitted as part of the MLC.

In an aspect, neighbor description information contained in the NDMmessage is generated separately for each LOI and is configured toprovide a list of RF channels associated with a selected LOI and itsneighboring LOs. In another aspect, a NDM message is generated for aselected group of LOIs (which may or may not be neighbors), and includesall neighboring LOIs for each of the LOI within the selected group ofLOs. Each of the RF channels described in the neighbor descriptioninformation is associated with WID/LID descrambling identifiers.

In an aspect, the NDM message is distributed over a LOI using a localcontrol channel that is part of the transmission frames transmitted bythe RF channels in that LOI. It should be noted that the neighbordescription information carried in the NDM may be formatted in anysuitable format, encoded or encrypted, and/or reorganized or dividedinto two or more message components.

A table 214 illustrates how parameters provided in the NDM message maybe organized and stored at a device. The table 214 comprises a LOIidentifier 216 that identifies the device's current LOI (i.e., LOI2).The table 214 also includes a Neighbor LOI List 218 that identifiesneighboring LOIs of the device's current LOI plus the current LOIitself. The table 214 also includes RF channel identifiers 220, whichindicate identifiers that may be used to reference to particular RFchannels of the current LOI in other control channel messages. Note thatthe RF channel identifiers 220 are only provided for the current LOI(i.e., LOI2). The table 214 also comprises RF Frequency identifiers 222that identify RF frequencies associated with each LOI identified in theNeighbor LOI List 218. The table 214 also comprises WID/LID Identifiers224 that identify WID/LID descrambling sequence identifiers associatedwith each RF Frequency 222. Thus, the table 214 may be created andstored at a receiving device and used during operation of the handoffsystem.

FIG. 3 shows RF handoff logic 300 for use in aspects of a handoffsystem. For example, the RF handoff logic 300 is suitable for use as theRF handoff logic 118 shown in FIG. 1. The RF handoff logic 300 comprisesprocessing logic 302, message decoder 304, channel switch logic 310, andoverhead input logic 306 all coupled to a data bus 308.

The overhead input logic 306 comprises at least one of a CPU, processor,gate array, hardware logic, memory elements, and/or hardware executingsoftware. The overhead input logic 306 operates to receive OIS andcontrol channel data over an RF channel to which a device is currentlytuned. The overhead input logic 306 passes the received CC data to themessage decoder 304. For example, the overhead input logic 306 operatesto receive an NDM message that is transmitted over a local controlchannel as illustrated in FIG. 2.

The message decoder 304 comprises at least one of a CPU, processor, gatearray, hardware logic, memory elements, and/or hardware executingsoftware. In an aspect, the message decoder 304 operates to decode anNDM message received by the control channel input logic 306. Forexample, the message decoder 304 operates to decode the received NDMmessage to determine available RF channels associated with the currentLOI and its neighboring LOs. The message decoder 304 decodes thereceived NDM message to determine WID/LID descrambling sequenceidentifiers associated with each RF channel in the device's current LOIand its neighboring LOs. For example, the information received in theNDM message is organized and stored as illustrated in FIG. 2 to providethe WID/LID descrambling identifiers associated with RF channels in thedevice's current LOI and its neighboring LOs.

The processing logic 302 comprises at least one of a CPU, processor,gate array, hardware logic, memory elements, and/or hardware executingsoftware. In an aspect, the processing logic 302 operates to receive ahandoff event which indicates that an RF handoff is desired because ofdata acquisition failures associated with desired content due tochanging network conditions (e.g. due to device mobility) or otherreasons. In such a case, it may be necessary to perform a handoff toswitch to an RF channel in a neighboring LOI which carries the desiredcontent to continue to receive the desired content.

The processing logic 302 operates to process information received in theNDM to generate seamless and partially seamless handoff tables fordesired content. In an aspect, the processing logic 302 assembles thehandoff tables to comprise those RF channels in neighboring LOIs thatare associated with the WID/LID of the desired content. In an aspect,neighboring RF channels associated with same WID carry same wide areacontent and neighboring RF channels associated with same LID carry samelocal area content. In an aspect, handoff tables comprise wide, local,and wide+local seamless and partially seamless handoff tables.

Once the RF channels in the handoff tables are determined, theprocessing logic 302 operates to determine signal strength informationrelated to those RF channels. For example, the processing logic 302operates to perform RF monitoring for neighboring RFs to receive signalstrength parameters associated with RF channels identified in theseamless and partially seamless handoff tables. For example, in anaspect, this information is obtained from a device receiver, such as thereceiver 116 shown in FIG. 1.

The processing logic 302 also operates to determine information aboutthe content available in the LOIs associated with each RF channel in thehandoff tables. For example, the content information comprises thenumber of available common multiplexes with the current LOI and thetotal number of available multiplexes in each identified LOI. Theprocessing logic 302 operates to use the content information to rank RFchannels in the seamless and partially seamless handoff tables.

The processing logic 302 operates to receive a handoff event. Thehandoff event indicates that a handoff to another RF channel is neededto continue to acquire the desired content. For example, the handoffevent may indicate that a handoff is desired because of contentacquisition failures for the desired content e.g. due to changingnetwork conditions.

Once the handoff event is detected for desired content, the processinglogic 302 operates to process RF channels in the seamless handoff tableassociated with the desired content to determine a selected RF channelfor handoff. If there are no RF channels in the associated seamlesshandoff table or if none of the RF channels in the associated seamlesshandoff table meet RF selection criteria, then the processing logic 302processes RF channels in the partially seamless handoff table associatedwith the desired content to determine the selected RF channel forhandoff. The processing logic 302 operates to process RF channels in theseamless handoff table and the partially seamless handoff table in theirranking order. Once the selected RF channel is determined, theprocessing logic 302 passes the identity of this RF channel to thechannel switch logic 310. A more detailed description of the operationof the processing logic 302 to select the selected RF channel from thehandoff tables and details of RF selection criteria is provided inanother section of this document.

The channel switch logic 310 comprises at least one of a CPU, processor,gate array, hardware logic, memory elements, and/or hardware executingsoftware. The channel switch logic 310 operates to generate an RFchannel switch message that comprises the identity of the selected RFchannel and its WID/LID descrambling sequence identifiers. The RFchannel switch message is sent to the device receiver 116. With thisinformation, the receiver 116 can quickly switch to the selected RFchannel and use the received WID/LID descrambling sequences to receivethe desired content. Thus, during a handoff, an RF channel can beselected that provides the desired content, meets the RF selectioncriteria, and is ranked highest from the perspective of common content(with current LOI) and additional content carried in the associated LOIfor an enhanced user experience.

In an aspect, the handoff system comprises a computer program producthaving one or more program instructions (“instructions”) or sets of“codes” stored or embodied on a machine-readable medium, which whenexecuted by at least one processor, for instance, a processor at theprocessing logic 302, causes a computer to provide the functionsdescribed herein. For example, the sets of codes may be loaded into theRF handoff logic 300 from a machine-readable medium, such as a floppydisk, CDROM, memory card, FLASH memory device, RAM, ROM, or any othertype of memory device or machine-readable medium that interfaces to theRF handoff logic 300. In another aspect, the sets of codes may bedownloaded into the RF handoff logic 300 from an external device ornetwork resource. The sets of codes, when executed, cause a computer toprovide aspects of a handoff system as described herein.

RF Channel Monitoring

In an aspect, the handoff system at the device operates to performmonitoring of RF channels carried in the device's current andneighboring LOIs to maintain information related to signal strength forthese RF channels. For example, the processing logic 302 operates toobtain a received signal strength indicator (RSSI) for RF channels inthe current LOI and neighboring LOs. For each available RF channel, theprocessing logic 302 may also maintain timestamps associated with RSSImeasurements. The timestamps associated with RSSI measurements can beused to invalidate old RSSI entries. The processing logic 302 operatesto maintain tables of RF channel monitoring information in a localmemory. During handoff, the processing logic 302 utilizes informationcollected during RF channel monitoring to select an RF channel forhandoff purposes. For example, signal strength information is used toevaluate RF channels in seamless and partially seamless handoff tablesfor handoff purposes.

Wide and Local Content Handoff

In an aspect, the handoff system operates to initiate RF handoff basedon handoff events. The RF handoff can be initiated for wide contentflows and/or local content flows. In an aspect, if a device isattempting to decode only desired wide content flows and contentacquisition failures are detected, a wide content RF handoff will beinitiated. In an aspect, if device is attempting to decode only desiredlocal content flows and content a acquisition failures are detected, alocal content RF handoff will be initiated. In another aspect, if deviceis attempting to decode both desired wide and local flows and contentacquisition failures are detected, a wide+local content RF handoff willbe initiated. A wide content RF handoff is targeted to handoff to an RFwhich carries at least the desired wide content. A local content RFhandoff is targeted to handoff to an RF which carries at least thedesired local content and a wide+local content RF handoff is targeted tohandoff to an RF which carries both the desired wide and local content.A specific RF handoff type (wide, local or wide+local) will initiate ahandoff to an RF channel in an associated seamless or partially seamlesshandoff table. For example, a wide content RF handoff will initiate ahandoff to an RF channel in the seamless or partially seamless handofftable associated with the desired wide content.

Real Time and Non Real Time Content Handoff

A handoff event can be initiated when a device is attempting to acquirereal time content flows and content acquisition failures occur. Ahandoff event can also be initiated when the device is attempting toacquire non real time content flows and content acquisition failuresoccur. Real time flows are also referred to as activated flows and nonreal time flows are also referred to as registered flows. A dataacquisition procedure to capture data for these flows can be performedin a variety of ways. For example, one data acquisition procedure tocapture data for activated (real time) and registered (non real time)flows is provided in the above referenced application (ProvisionalApplication No. 60/910,191, entitled “Methods and Apparatus forProviding Flow Data Acquisition Priority Scheme in a Multiple FrequencyNetwork,” filed Apr. 4, 2007, and to Provisional Application No.60/945,317, entitled “Methods And Apparatus for Providing Flow DataAcquisition Priority Scheme in a Multiple Frequency Network,” filed Jun.20, 2007). The handoff process to execute RF handoff is same for bothactivated and registered flows, although the handoff process may operatefor different timer periods for activated and registered flows. Adetailed description of the handoff process for activated and registeredflows is captured in other sections of this document.

Handoff Event Trigger Criteria

In an aspect, a handoff event is triggered by certain criteria relatedto activated and registered flows. Handoff event trigger criteria areevaluated separately for activated and registered flows. If bothactivated and registered flows are being decoded, then handoff eventtrigger criteria are evaluated for activated flows only. This is becauseactivated flows (i.e. real time flows) are given higher priority thanregistered flows (i.e. non real time flows). The failure to acquire anappropriate set of overhead information which includes OIS and controlchannel (CC) will trigger a handoff event for both activated andregistered flows. The overhead information is used to acquire flow datafor activated and registered flows.

In various aspects, one or more of the following conditions trigger ahandoff event for activated flows.

-   1. Acquisition of the appropriate OIS and control channel (CC) (if    required) fail for desired wide and/or local activated flows. For    example if only wide activated flows are being decoded, then WOIS    and wide CC fail on the current RF.-   2. Data acquisition fails for all activated flows on the current RF.-   3. Acquisition of local OIS and local CC (if required) fail if both    wide and local activated flows are being decoded on current RF    channel.-   4. Data acquisition fails for a subset of activated flows on the    current RF.

For the acquisition of registered flows, the device determines aselected flow group (FG) and attempts to decode registered flowsassociated with that selected FG. For example, in an aspect, a flowgroup comprises a grouping of non real time data flows that are groupedtogether based on selected criteria, such as priority. An example ofvarious types of flow groups is provided in the above referencedapplication (Provisional Application No. 60/910,191, entitled “methodsand Apparatus for Providing Flow Data Acquisition Priority Scheme in aMultiple Frequency Network,” filed Apr. 4, 2007, and to ProvisionalApplication No. 60/945,317, entitled “Methods And Apparatus forProviding Flow Data Acquisition Priority Scheme in a Multiple FrequencyNetwork,” filed Jun. 20, 2007). The device also attempts to decode anyother registered flows carried by the same RF channel as the selectedFG. In various aspects, one or more of the following conditions triggera handoff event for registered flows:

-   1. Acquisition of appropriate OIS and CC (if required) fail for wide    and/or local registered flows in the selected flow group (FG). For    example if selected FG has only wide registered flows, then WOIS and    wide CC fail.-   2. Data acquisition fails for all registered flows in selected FG.-   3. Acquisition of local OIS and local CC (if required) fails if    selected FG includes both wide and local registered flows.-   4. Data acquisition fails for a subset of registered flows in    selected FG.

Seamless Handoff Tables

In an aspect, the handoff system operates to generate and maintainseamless handoff tables for wide and local content multiplexes carriedon RF channels in the current LOI. In an aspect, a seamless handofftable for a given wide or local content multiplex includes neighboringRF channels that carry the same given wide or local content multiplex,respectively, and the LOI associated with the neighboring RF channelcarries the same set or a superset of wide or local content multiplexes,respectively, as carried in the current LOI. In an aspect, a seamlesshandoff table for a given combination of wide+local multiplexes includesneighboring RF channels that carry the same combination of wide+localcontent multiplexes and the LOI associated with the neighboring RFcarries the same set or a superset of wide and local content multiplexesas carried in the current LOI. The neighboring RFs included in a givenseamless handoff table are referred to as seamless RFs for theassociated content multiplex(es).

The following types of seamless handoff tables are maintained:

-   a. Wide seamless handoff table: A separate wide seamless handoff    table is generated and maintained for each wide content multiplex    carried in the current LOI. This table identifies neighboring RF    channels that carry the same wide content multiplex and their    associated LOI carries same set or a superset of wide content    multiplexes as the current LOI.-   b. Local seamless handoff table: A separate local seamless handoff    table is generated and maintained for each local content multiplex    carried in the current LOI. This table identifies neighboring RF    channels that carry the same local content multiplex and their    associated LOI carry same set or a superset of local content    multiplexes as the current LOI.-   c. Wide+Local seamless handoff table: A separate wide+local seamless    handoff table is generated and maintained for each combination of    wide+local content multiplexes carried on a single RF in the current    LOI. This table identifies neighboring RF channels that carry the    same combination of wide+local content multiplexes and their    associated LOI carries same set or a superset of wide+local content    multiplexes as the current LOI.

Depending on the content carried by neighboring RFs, seamless handofftables may be empty for one or more of the content multiplexes (wide,local or wide+local) carried in current LOI. In an aspect, the seamlesshandoff table maintains information for each seamless RF channel relatedto: i) total number of wide and local content multiplexes that arecommon between the LOI associated with that seamless RF channel and thedevice's current LOI; and ii) overall total number of contentmultiplexes carried in the LOI associated with that seamless RF channel.The information (i) and (ii) maintained for seamless RF channels is usedto rank these RF channels for the purpose of executing RF handoff.

FIG. 4 shows an exemplary seamless handoff table 400 applicable for useas a wide or local seamless handoff table in aspects of a handoffsystem. In an aspect, the seamless handoff table 400 is generated by theprocessing logic 302. The seamless handoff table 400 comprises a contentmultiplex identifier 402 which identifies the wide or local contentmultiplex for which this seamless handoff table is generated. Theseamless handoff table 400 also comprises a {RF, LOI} Identifier 404that identifies an RF frequency and associated neighboring LOI thatcarries the wide or local content multiplex identified by the contentmultiplex identifier 402. The seamless handoff table 400 also comprisesan overall number of common multiplexes indicator 406 that indicates thetotal number of multiplexes that are common between the LOI associatedwith the identified seamless RF and the current LOI. The seamlesshandoff table 400 also comprises a total number of multiplexes indicator408 that indicates the total number of multiplexes available in the LOIassociated with the identified seamless RF.

FIG. 5 shows an exemplary wide+local seamless handoff table 500applicable for use in a wide+local seamless handoff in aspects of ahandoff system. In an aspect, the wide+local seamless handoff table 500is generated by the processing logic 302. The wide+local seamlesshandoff table 500 comprises a content multiplex identifier 502 whichidentifies the combination of wide+local content multiplexes for whichthis seamless handoff table is generated. The wide+local seamlesshandoff table 500 also comprises a {RF, LOI} Identifier 504 thatidentifies an RF frequency and associated neighboring LOI that carry thewide+local content multiplexes identified by the content multiplexidentifier 502. The seamless handoff table 500 also comprises a totalnumber of multiplexes indicator 506 that indicates the total number ofmultiplexes available in the LOI associated with the identified seamlessRF.

Partially Seamless Handoff Tables

In an aspect, the handoff system operates to generate and maintainpartially seamless handoff tables for wide and local content multiplexescarried on RF channels in the current LOI. In an aspect, a partiallyseamless handoff table for a given wide or local content multiplexincludes neighboring RF channels that carry the same given wide or localcontent multiplex respectively, and the LOI associated with theneighboring RF does not carry the same set or a superset of wide orlocal content multiplexes respectively, as carried in the current LOI.In an aspect, a partially seamless handoff table for a given combinationof wide+local multiplexes includes neighboring RF channels that carrythe same combination of wide+local content multiplexes and the LOIassociated with the neighboring RF does not carry the same set or asuperset of wide and local content multiplexes as carried in the currentLOI. The neighboring RFs included in a given partially seamless handofftable are referred to as partially seamless RFs for the associatedcontent multiplex(es). As per the definition, the sets of seamless RFsand partially seamless RFs for a given content multiplex are disjoint.

In various aspects, the following types of partially seamless handofftables are maintained.

-   a. Wide partially seamless handoff table: A separate wide partially    seamless handoff table is generated and maintained for each wide    content multiplex carried in the current LOI. This table identifies    neighboring RF channels that carry the same wide content multiplex    and their associated LOI does not carry same set or a superset of    wide content multiplexes as the current LOI.-   b. Local partially seamless handoff table: A separate local    partially seamless handoff table is generated and maintained for    each local content multiplex carried in the current LOI. This table    identifies neighboring RF channels that carry the same local content    multiplex and their associated LOI does not carry same set or a    superset of local content multiplexes as the current LOI.-   c. Wide+Local partially seamless handoff tables: A separate    wide+local partially seamless handoff table is generated and    maintained for each combination of wide+local content multiplexes    carried on a single RF in the current LOI. This table identifies    neighboring RF channels that carry the same combination of    wide+local content multiplexes and their associated LOI does not    carry same set or a superset of wide+local content multiplexes as    the current LOI.

Depending on the content carried by neighboring RFs, partially seamlesshandoff tables may be empty for one or more of the content multiplexes(wide, local or wide+local) carried in current LOI. In an aspect, thepartially seamless handoff table maintains information for eachpartially seamless RF channel related to: i) total number of wide andlocal content multiplexes that are common between the LOI associatedwith that partially seamless RF channel and the device's current LOI;and ii) overall total number of content multiplexes carried in LOIassociated with that partially seamless RF channel. The information (i)and (ii) maintained for partially seamless RF channels is used to rankthese RF channels for the purpose of executing RF handoff.

FIG. 6 shows an exemplary partially seamless handoff table 600applicable for use as a wide, local, or wide+local partially seamlesshandoff table for use in aspects of a handoff system. In an aspect, thepartially seamless handoff table 600 is generated by the processinglogic 302. The partially seamless handoff table 600 comprises a contentmultiplex identifier 602 which identifies the wide, local or wide+localcontent multiplexes for which this partially seamless handoff table isgenerated. The partially seamless handoff table 600 also comprises a{RF, LOI} Identifier 604 that identifies an RF frequency and associatedneighboring LOI that carries the wide, local or wide+local contentmultiplexes identified by the content multiplex identifier 602.

The partially seamless handoff table 600 also comprises an overallnumber of common multiplexes indicator 606 that indicates the totalnumber of multiplexes that are common between the LOI associated withthe identified partially seamless RF and the current LOI. The partiallyseamless handoff table 600 also comprises a total number of multiplexesindicator 608 that indicates the total number of multiplexes availablein the LOI associated with the identified partially seamless RF.

HANDOFF TABLE EXAMPLES

FIG. 13 shows examples of seamless handoff tables 1300 for use inaspects of a handoff system. For example, it will be assumed that thedevice 112 is currently located in LOI2 and is operable to receivecontent multiplexes associated with WID1, WID2, LID1, LID2 that aretransmitted on RF2 or RF3 in LOI2. Thus, the seamless handoff tables1300 reflect the distribution of content in the network configurationillustrated in FIG. 1 as it relates to the device 112 operating in theLOI2.

Wide seamless handoff tables associated with wide content in LOI2 areshown at 1302 and 1304. The wide seamless handoff table 1302 isassociated with a wide content multiplex identified by WID1 and includesseamless RF channel RF4 in LOI3, which carries the same wide contentmultiplex. In addition, the table 1302 shows that LOI3 has four (4)multiplexes in common with LOI2 and that the total number of multiplexescarried in LOI3 is four (4).

The wide seamless handoff table 1304 is associated with a wide contentmultiplex identified by WID2 and includes seamless RF channel RF5 inLOI3, which carries the same wide content multiplex. In addition, thetable 1304 shows that LOI3 has four (4) multiplexes in common with LOI2and that the total number of multiplexes carried in LOI3 is four (4).

Local seamless handoff tables are shown at 1306 and 1308. The localseamless handoff table 1306 is associated with a local content multiplexidentified by LID1 and includes seamless RF channel RF4 in LOI3 whichcarries the same local content multiplex. In addition, the table 1306shows that LOI3 has four (4) multiplexes in common with LOI2 and thatthe total number of multiplexes in LOI3 is four (4).

The local seamless handoff table 1308 is associated with a local contentmultiplex identified by LID2 and includes seamless RF channel RF5 inLOI3 which carries the same local content multiplex. In addition, thetable 1308 shows that LOI3 has four (4) multiplexes in common with LOI2and that the total number of multiplexes in LOI3 is four (4).

Wide+local seamless handoff tables are shown at 1310 and 1312. Thewide+local seamless handoff table 1310 is associated with a combinationof wide+local content multiplexes identified by WID1+LID1 and includesseamless RF channel RF4 in LOI3, which carries the same combination ofwide+local content multiplexes. In addition, the table 1310 shows thatthe total number of multiplexes in LOI3 is four (4).

The wide+local seamless handoff table 1312 includes is associated with acombination of wide+local content multiplexes identified by WID2+LID2and includes seamless RF channel RF5 in LOI3 which, carries the samecombination of wide+local content multiplexes. In addition, the table1308 shows that the total number of multiplexes in LOI3 is four (4).

Thus, the seamless handoff tables 1300 identify wide and/or localcontent multiplexes in LOI2, seamless RF channels and their associatedLOI identifiers for these content multiplexes, and multiplex informationfor LOIs associated with seamless RFs for use in aspects of a handoffsystem.

FIG. 14 shows examples of partially seamless handoff tables 1400 for usein aspects of a handoff system. For example, it will be assumed that thedevice 112 is currently located in LOI2 and is operable to receivecontent multiplexes associated with WID1, WID2, LID1, LID2 that aretransmitted on RF2 or RF3 in LOI2. Thus, the partially seamless handofftables 1400 reflect the distribution of content in the networkconfiguration illustrated in FIG. 1 as it relates to the device 112operating in the LOI2.

A wide partially seamless handoff table is shown at 1402. The widepartially seamless handoff table 1402 is associated with a wide contentmultiplex identified by WID1 and includes partially seamless RF channelsRF1 in LOI1, and RF6 in LOI4, which carry the same wide contentmultiplex. For LOI1, the table 1402 shows that it has one (1) multiplexin common with LOI2 and that the total number of multiplexes in LOI1 istwo (2). For LOI4, the table 1402 shows that it has two (2) multiplexesin common with LOI2 and that the total number of multiplexes in LOI4 istwo (2).

A local partially seamless handoff table is shown at 1404. The localpartially seamless handoff table 1404 is associated with a local contentmultiplex identified by LID1 and includes partially seamless RF channelRF6 in LOI4, which carries the same local content multiplex. Inaddition, the table 1404 shows that LOI4 has two (2) multiplexes incommon with LOI2 and that the total number of multiplexes in LOI4 is two(2).

A wide+local partially seamless handoff table is shown at 1406. Thewide+local partially seamless handoff table 1406 is associated with acombination of wide+local content multiplexes identified by WID1+LID1and includes seamless RF channel RF6 in LOI4, which carries the samecombination of wide+local content multiplexes. In addition, the table1406 shows that LOI4 has two (2) multiplexes in common with LOI2 andthat the total number of multiplexes in LOI4 is two (2). It should benoted that partially seamless handoff tables for WID2, LID2 andWID2+LID2 are empty and therefore not shown.

Thus the partially seamless handoff tables 1400 identify wide and/orlocal content multiplexes in LOI2, partially seamless RF channels andtheir associated LOI identifiers for these content multiplexes, andmultiplex information for LOIs associated with partially seamless RFsfor use in aspects of a handoff system.

RF Channel Ranking

In an aspect, RF channels in seamless and partially seamless handofftables are ranked based on information maintained in these tables.Neighboring RF channels included in seamless and partially seamlesshandoff tables are ranked to achieve: i) Maximizing number of wideand/or local content multiplexes that are common between LOI associatedwith neighboring RF channel and device's current LOI; and ii) Maximizingoverall total number of content multiplexes in LOI associated withneighboring RF channel. The neighboring seamless and partially seamlessRF channels are evaluated in their ranking order for handoff executionto provide enhanced user experience. In various aspects, neighboring RFchannels in wide or local seamless handoff table are ranked as follows.

-   1. The RF channel with more number of common multiplexes (with    device's current LOI) in associated LOI is assigned higher rank.-   2. Among RF channels with same number of common multiplexes with    device's current LOI, RF channel with more number of overall    multiplexes in associated LOI is assigned higher rank.-   3. Among RF channels with same number of overall multiplexes, RF    channels can be assigned ranking in any random order.

In various aspects, neighboring RF channels in wide+local seamlesshandoff table are ranked as follows.

-   1. The RF channel with more number of overall multiplexes in    associated LOI is assigned higher rank.-   2. Among RF channels with same number of overall multiplexes, RF    channels can be assigned ranking in any random order.

In various aspects, neighboring RF channels in wide, local andwide+local partially seamless handoff tables are ranked as follows.

-   1. RF channel with more number of common multiplexes (with current    LOI) in associated LOI is assigned higher rank.-   2. Among RF channels with same number of common multiplexes in    associated LOI, RF channel with more number of overall multiplexes    is assigned higher rank.-   3. Among RF channels with same number of overall multiplexes in    associated LOI, RF channels can be assigned ranking in any random    order.

In another aspect, RSSI values (if available) for RF channels carryingcommon wide and/or local content multiplexes in associated LOIs can alsobe used to rank seamless and partially seamless RF channels. Theseamless and partially seamless RF channels which have higher RSSIvalues associated with RF channels carrying common wide and/or localcontent multiplexes in associated LOIs can be assigned higher rank. Thiswill provide better availability of common multiplexes in the new LOIafter handoff. The seamless and partially seamless RF channels areevaluated in their ranking order for executing an RF handoff. In anaspect, a seamless or a partially seamless RF channel is considered fora handoff only if it meets a signal strength criteria where RSSI for theRF channel is greater than a defined threshold.

Handoff Overview

An RF handoff to an RF channel in a neighboring LOI is initiatedwhenever a handoff event (i.e., content acquisition failures) isdetected for desired content. The RF channels in seamless and partiallyseamless handoff tables associated with desired content are consideredfor performing the handoff. A handoff RF list is generated by combiningseamless and partially seamless RF channels associated with desiredcontent. Seamless RF channels are listed higher than partially seamlessRF channels in the handoff RF list. Also, individual set of seamless andpartially seamless RF channels are listed in their respective rank orderin the handoff RF list. The RFs in the handoff RF list are evaluated forhandoff in their listed order.

A Handoff_Trigger_RF parameter is maintained which specifies the currentRF channel when the handoff event was first initiated. To perform ahandoff to a particular neighboring RF, that neighboring RF should meetRF selection criteria. Meeting the RF selection criteria involvesmeeting a signal strength criterion where the RSSI of the selected RFchannel should be greater than a defined threshold and meeting a handoffcriterion. The handoff criterion is evaluated with respect to theHandoff_Trigger_RF. In an aspect, a neighboring RF meets the handoffcriterion if the following holds true.

RSSI of neighboring RF>=RSSI of Handoff_Trigger_RF+RSSI_Hystersis  (1)

The RSSI_Hysteresis is used to minimize ping ponging between theneighboring RF and the Handoff_Trigger RF. The Handoff_Trigger_RFparameter gets set to the neighboring RF if the WOIS is acquiredsuccessfully on that neighboring RF.

The handoff to RFs in the set of neighboring seamless and partiallyseamless RFs for the desired content is attempted for a finite timeperiod. A handoff timer is maintained to specify the time duration forwhich handoff should be executed. The handoff timer may be set todifferent values for activated and registered flows. For example, thehandoff timer can be set to a larger value for activated flows ascompared to registered flows because of real time nature of activatedflows. If desired content can not be acquired after the handoff timerexpires, the system gives up attempting to acquire the desire content.The device behavior for activated and registered flows after the handofftimer expires is captured in another section in this document.

FIG. 7 shows a method 700 for performing a handoff for use in aspects ofa handoff system. For clarity, the method 700 is described herein withreference to the handoff logic 300 shown in FIG. 3. For example, in anaspect, the processing logic 302 executes one or more sets of codes tocontrol the handoff logic 300 to perform the functions described below.

At block 702, neighbor description information is received as part ofthe NDM. For example, the neighbor description information identifiesneighboring LOIs of the device's current LOI, their associated RFchannels, and the multiplexes carried on those RF channels (identifiedby WID and LID information). In an aspect, the neighbor descriptioninformation is received over a control channel by the control channellogic 306 and passed to the message decoder 304 where the information isdecoded for use by the processing logic 302.

At block 704, the RF channels in the current LOI and its neighboringLOIs are monitored to measure signal strengths (RSSI) for these RFchannels. In an aspect, the processing logic 302 operates to request andreceive signal strength parameters related to the RFs in the current andneighboring LOs.

At block 706, seamless handoff tables are generated and maintained. Inan aspect, the processing logic 302 operates to generate and maintainseamless handoff tables based on the received neighbor descriptioninformation. For example, for each multiplex in the current LOI, wideand local seamless handoff tables are formatted as illustrated in FIG.4, and wide+local seamless handoff tables are formatted as illustratedin FIG. 5.

At block 708, partially seamless handoff tables are generated andmaintained. In an aspect, the processing logic 302 operates to generateand maintain partially seamless handoff tables based on the receivedneighbor description information. For example, for each multiplex in thecurrent LOI, wide, local, and wide+local partially seamless handofftables are formatted as illustrated in FIG. 6.

At block 710, a determination is made as to whether a handoff event fordesired content has been detected. In an aspect, the processing logic302 operates to detect a handoff event. In an aspect, a handoff event istriggered as the result of acquisition failures associated with desiredcontent. For example acquisition failures may occur due to devicemobility. If a handoff event is not detected, the handoff method ends.If a handoff event is detected, the method proceeds to block 712.

At block 712, a determination is made as to whether there are any RFchannels in the seamless handoff table associated with the desiredcontent. In an aspect, the processing logic 302 makes this determinationbased on set of seamless handoff tables maintained. If there are any RFchannels in the seamless handoff table associated with the desiredcontent, the method proceeds to block 714. If there are no RF channelsin the seamless handoff table associated with the desired content, themethod proceeds to block 732.

At block 714, the RF channels in the seamless handoff table associatedwith the desired content are sorted by increasing rank. In an aspect,the processing logic 302 operates to perform this sorting according tothe ranking algorithms described above.

At bloc 716, a determination is made as to whether there are any RFchannels in the partially seamless handoff table associated with thedesired content. In an aspect, the processing logic 302 makes thisdetermination based on the set of partially seamless handoff tablesmaintained. If there are RF channels available in the partially seamlesshandoff table associated with the desired content, the method proceedsto block 718. If there are no RF channels in the partially seamlesshandoff table associated with the desired content, the method proceedsto block 722.

At block 718, the RF channels in the partially seamless handoff tableassociated with the desired content are sorted by increasing rank. In anaspect, the processing logic 302 operates to perform this sortingaccording to the ranking algorithms described above.

At block 720, a handoff RF list is generated that comprises the sortedseamless RF channels followed by the sorted partially seamless RFchannels. In an aspect, the processing logic 302 operates to generatethe handoff RF list.

At block 722, a handoff RF list is generated that comprises the sortedseamless RF channels. In an aspect, the processing logic 302 operates togenerate the handoff RF list.

At block 724, a determination is made as to whether the detected handofftrigger event is based on one of the first or second handoff triggerconditions out of the four handoff trigger conditions described above.In an aspect, the processing logic 302 makes this determination. If thehandoff event is based on the first or second trigger condition, themethod proceeds to block 728. If the handoff event is not based oneither of the first or second trigger conditions, the method proceeds toblock 726.

At block 726, the Handoff_Trigger-RF is assigned to the current RFchannel. In an aspect, the processing logic 302 makes this assignment.

At block 728, a handoff timer is started. In an aspect, the handofftimer is maintained by the processing logic 302, which operates to startthe timer. In an aspect, the handoff timer parameter may be set todifferent values for handoffs initiated for activated and registeredflows.

At block 730, a handoff procedure is executed based on the currenthandoff RF list. In an aspect, the handoff procedure is provided by themethod 800 shown in FIG. 8.

At block 732, a determination is made as to whether there are any RFchannels in the partially seamless handoff table associated with thedesired content. In an aspect, the processing logic 302 makes thisdetermination based on set of partially seamless handoff tablesmaintained. If there are any RF channels in the partially seamlesshandoff table associated with the desired content, the method proceedsto block 734. If there are no RF channels in the partially seamlesshandoff table associated with the desired content, the method proceedsto block 738.

At block 734, the RF channels in the partially seamless handoff tableassociated with the desired content are sorted by increasing rank. In anaspect, the processing logic 302 operates to perform this sortingaccording to the ranking algorithms described above.

At block 736, a handoff RF list is generated that comprises the sortedpartially seamless RF channels. In an aspect, the processing logic 302operates to generate the handoff RF list.

At block 738, a determination is made as to whether the handoff type isa wide+local handoff. In an aspect, the processing logic 302 makes thisdetermination. If the handoff is a wide+local handoff, the methodproceeds to block 742. If the handoff is not a wide+local handoff, themethod proceeds to block 740.

At block 740, an attempt is made to acquire the desired content on an RFchannel in the current LOI. This is because at this point in the method700, it has been determined that there are no seamless or partiallyseamless RF channels available for the desired content.

At block 742, the handoff type is wide+local and no seamless orpartially seamless RF channels are available for the desired wide+localcontent. As a result, an attempt is made to perform a wide handoff forthe desired wide content. If the wide handoff fails, an attempt is madeto perform a local handoff for the desired local content.

Thus, the method 700 operates to perform a handoff for use in aspects ofa handoff system. It should be noted that the method 700 represents justone implementation and that other implementations are possible withinthe scope of the aspects.

FIG. 8 shows a method 800 for performing a handoff procedure for use inaspects of a handoff system. For example, the method 800 is suitable foruse at block 730 of the method 700. For clarity, the method 800 isdescribed herein with reference to the handoff logic 300 shown in FIG.3. For example, in an aspect, the processing logic 302 executes one ormore sets of codes to control the handoff logic 300 to perform thefunctions described below.

At block 802, an Acquisition RF list is set to be equivalent to thecurrent handoff RF list. In an aspect, the handoff RF list is determinedby the processing logic 302 as discussed above with reference to themethod 700.

At block 804, RF channels in the Acquisition RF list are monitored tomeasure signal strength (RSSI) for these RF channels. In an aspect, theprocessing logic 302 operates to communicate with receiving logic at thedevice to request the RF signal strength characteristic of RFs in theAcquisition RF list.

At block 806, a determination is made as to whether the signal strengthof all RFs in the Acquisition RF list is less than a selected signalstrength threshold. In an aspect, the processing logic 302 operates tocompare the signal strength characteristics of all RFs in theAcquisition RF list to a selected threshold value to make thisdetermination. If the signal strength of all RFs in the Acquisition RFlist is less than or equal to the threshold, the method proceeds toblock 808. If there are any RFs in the Acquisition RF list that have asignal strength greater than the selected threshold, the method proceedsto block 814.

At block 808, a determination is made as to whether a handoff timer hasexpired. In an aspect, the processing logic 302 maintains the handofftimer (at block 728) as discussed with reference to the method 700. Theprocessing logic 302 determines if the handoff timer has expired and ifso, the method proceeds to block 812. If the handoff timer has notexpired, the method proceeds to block 810.

At block 812, a handoff failure is declared. In an aspect, because allRFs in the Acquisition RF list that have a signal strength that is lessthan or equal to the selected threshold and the handoff timer hasexpired, the processing logic 302 determines that the attempted handoffhas failed.

At block 810, the Acquisition RF list is set to be equivalent to thecurrent handoff RF list. In an aspect, the handoff RF list is determinedby the processing logic 302 as discussed above with reference to themethod 700.

At block 814, the first RF channel with RSSI>Threshold is selected inthe ordered Acquisition RF list. Then an evaluation is performed toevaluate the handoff criterion for the selected RF channel. The handoffcriterion is evaluated as described by equation (1) above. In an aspect,the processing logic 302 makes the RF selection and handoff criteriaevaluation.

At block 816, a determination is made to determine if the handoffcriterion evaluated at block 814 is satisfied for the selected RFchannel. In an aspect, the processing logic 302 makes thisdetermination. If the handoff criteria are satisfied for the selected RFchannel in the Acquisition RF list, the method proceeds to block 818. Ifthe handoff criterion is not satisfied, the method proceeds to block820.

At block 820, the selected RF channel is removed from the Acquisition RFlist. In an aspect, the processing logic 302 removes the selected RFfrom the Acquisition RF list because this RF failed to meet the handoffcriteria as determined at block 816 or because the OIS could not besuccessfully acquired on selected RF as determined at block 830 orbecause acquisition for CC (if required) fails on the selected RF asdetermined at block 838 or because no MLC could be decoded successfullyas determined at block 842.

At block 822, a determination is made as to whether a handoff timer hasexpired. In an aspect, the processing logic 302 maintains the handofftimer as discussed with reference to the method 700. The processinglogic 302 determines if the handoff timer has expired and if so, themethod proceeds to block 824. If the handoff timer has not expired, themethod proceeds to block 826.

At block 824, a handoff failure is declared. In an aspect, because thehandoff timer has expired, the processing logic 302 determines that theattempted handoff has failed.

At block 826, if the Acquisition RF list is empty, the Acquisition RFlist is reset to be equivalent to the handoff RF list. In an aspect, theprocessing logic 302 determines if the Acquisition RF list is empty, andif so, resets it to the handoff RF list.

At block 818, a switch to the selected RF is performed using the WID/LIDassociated with the RF. In an aspect, the processing logic 302 controlsthe channel switch logic 310 to switch to the selected RF and use theassociated WID/LID to descramble content on that RF.

At block 828, an attempt is made to acquire the OIS on the selected RFchannel. In an aspect, the OIS is acquired by the overhead input logic306.

At block 830, a determination is made as to whether the OIS was acquiredsuccessfully on the selected RF. In an aspect, the processing logic 302makes this determination. If the OIS was not acquired successfully, themethod proceeds to block 832. If the OIS was acquired successfully, themethod proceeds to block 834.

At block 832, a switch is made to the Handoff_Trigger RF. In an aspect,the processing logic 302 controls the channel switch logic 310 to switchback to the Handoff_Trigger-RF because the OIS acquisition failed on theselected RF.

At block 834, a Handoff_Trigger RF is set to the current RF. In anaspect, the processing logic 302 performs this operation.

At block 836, an attempt is made to acquire the appropriate controlchannel if needed. In an aspect, the overhead input logic 306 performsthis operation.

At block 838, a determination is made as to whether the control channelwas acquired successfully. In an aspect, the processing logic 302 makesthis determination. If the control channel was not acquiredsuccessfully, the method proceeds to block 820. If the control channelwas acquired successfully, the method proceeds to block 840.

At block 840, an attempt is made to decode media logical channels (MLCs)from the current RF. In an aspect, receiving logic at the deviceattempts to decode the MLCs and reports the results to the processinglogic 302.

At block 842, a determination is made as to whether at least one MLCassociated with desired content was decoded successfully. In an aspect,the processing logic 302 makes this determination. If at least one MLCassociated with desired content was not decoded successfully, the methodproceeds to block 820. If at least one MLC associated with desiredcontent was decoded successfully, the method proceeds to block 844.

At block 844, the handoff is determined to be successful and the handoffprocedure ends. In an aspect, the processing logic 302 makes thisdetermination because at least one MLC associated with desired contentwas successfully decoded.

Thus, the method 800 operates to perform a handoff for use in aspects ofa handoff system. It should be noted that the method 800 represents justone implementation and that other implementations are possible withinthe scope of the aspects.

FIG. 9 shows a method 900 for providing a handoff event trigger foractivated flows for use in aspects of a handoff system. For clarity, themethod 900 is described herein with reference to the handoff logic 300shown in FIG. 3. For example, in an aspect, the processing logic 302executes one or more sets of codes to control the handoff logic 300 toperform the functions described below.

At block 902, one or more real time flows are successfully activated. Inan aspect, applications at the device attempt to acquire one or morereal time flows.

At block 904, a determination is made as to whether required controlchannel information is locally stored. In an aspect, the processinglogic 302 operates to determine if the required control channelinformation is locally stored. If the control channel data is locallystored, the method proceeds to block 906. If the control channel data isnot locally stored, the method proceeds to block 908.

At block 906, a switch is performed (if needed) to switch to the RFchannel carrying the newly activated flows. In an aspect, the processinglogic 302 controls the channel switch logic 310 to switch to the RFchannel carrying the newly activated flows. An RF switch will not berequired if the device's current RF is the RF carrying newly activatedflows.

At block 908, at attempt is made to acquire the appropriate set of OISand control channel information from the new RF channel. In an aspect,the overhead input logic 306 obtains the OIS and control channelinformation from the new RF channel.

At block 910, a determination is made as to whether the appropriate setof OIS and control channel information was successfully acquired. In anaspect, the processing logic 302 operates to make this determination. Ifthe OIS and control channel data was not successfully acquired, themethod proceeds to block 914. If the OIS and control channel data wassuccessfully acquired, the method proceeds to block 912.

At block 912, the newly activated flows are decoded on the new RF. In anaspect, receiving logic at the device operates to decode the newlyactivated flows.

At block 914, a handoff procedure is executed in an attempt to acquirethe activated flows on a neighboring RF channel. In an aspect, theprocessing logic 302 operates to execute the handoff procedure becausethe OIS and CC acquisition fails on the RF channel carrying activatedflows in current LOI. In an aspect, the handoff procedure is describedabove with reference to FIG. 8.

At block 916, a determination is made as to whether the handoff wassuccessful. In an aspect, the processing logic 302 makes thisdetermination. If the handoff was successful, the method proceeds toblock 912. If the handoff was not successful, the method proceeds toblock 918.

At block 918, the handoff has failed and all activated flows aredeactivated. In an aspect, the processing logic 302 operates todeactivate all the activated flows.

At block 920, system acquisition logic is executed. In an aspect, theprocessing logic 302 operates to initiate system acquisition logic toacquire the system because the handoff failed.

Thus, the method 900 operates to perform providing a handoff eventtrigger for activated flows for use in aspects of a handoff system. Itshould be noted that the method 900 represents just one implementationand that other implementations are possible within the scope of theaspects.

FIG. 10 shows a method 1000 for providing a handoff event trigger foractivated flows for use in aspects of a handoff system. For clarity, themethod 1000 is described herein with reference to the handoff logic 300shown in FIG. 3. For example, in an aspect, the processing logic 302executes one or more sets of codes to control the handoff logic 300 toperform the functions described below.

At block 1002, a device is currently decoding activated flows on acurrent RF channel.

At block 1004, a determination is made to determine whether dataacquisition for all MLCs associated with activated flows failed or OISacquisition failed on the current RF channel. In an aspect, theprocessing logic 302 makes this determination. If there are no MLCs andOIS failures, the method proceeds to block 1002. If there is either thefailure of all MLCs associated with activated flows or the failure ofOIS acquisition, then the method proceeds to block 1006.

At block 1006, a handoff procedure for activated flows is executed. Forexample, the handoff procedure described in FIG. 8 is executed to handoff to a new neighboring RF channel to successfully acquire OIS andactivated flows.

At block 1008, a determination is made as to whether the handoff wassuccessful. In an aspect, the processing logic 302 makes thisdetermination. If the handoff was successful, the method proceeds toblock 1010. If the handoff was not successful, the method proceeds toblock 1012.

At block 1010, the activated flows are decoded from the new RF channel.In an aspect, the device has handed off to a new RF channel and is ableto acquire the activated flows from that RF channel.

At block 1012, handoff has failed and all the activated flows aredeactivated. In an aspect, the processing logic 302 operates todeactivate the activated flow because the handoff to a different RFchannel was unsuccessful.

At block 1014, system acquisition logic is executed. In an aspect, theprocessing logic 302 operates to initiate system acquisition logic toacquire the system because the handoff failed.

Thus, the method 1000 operates to perform providing a handoff eventtrigger for activated flows for use in aspects of a handoff system. Itshould be noted that the method 1000 represents just one implementationand that other implementations are possible within the scope of theaspects.

FIG. 11 shows a method 1100 for providing a handoff trigger event forregistered flows for use in aspects of a handoff system. In an aspect,the method 1100 initiates a handoff in the event of data acquisitionfailure with respect to registered flows. It should be noted that adetailed description of a data acquisition procedure (DAP) forregistered flows is not presented and specific embodiments of such adata acquisition procedure are not essential to the operation of themethods and apparatus of the various embodiments described herein.However, an example of a data acquisition procedure for registered flowscan be found in the above referenced application (ProvisionalApplication No. 60/910,191, entitled “methods and Apparatus forProviding Flow Data Acquisition Priority Scheme in a Multiple FrequencyNetwork,” filed Apr. 4, 2007, and to Provisional Application No.60/945,317, entitled “Methods And Apparatus for Providing Flow DataAcquisition Priority Scheme in a Multiple Frequency Network,” filed Jun.20, 2007). In an aspect, the processing logic 302 executes one or moresets of codes to control the handoff logic 300 to perform the functionsdescribed below.

At block 1102, a determination is made as to whether required controlchannel information is locally stored. In an aspect, the processinglogic 302 operates to make this determination. If the required controlchannel information is locally stored, the method proceeds to block1104. If the control channel information is not locally stored, themethod proceeds to block 1108.

At block 1104, flow groups (FGs) comprising registered flows for whichdata is to be acquired are stored in the DAP_FG[.] list in their rankorder. The highest rank FG (DAP_FG[0]) is selected for acquiringregistered flow data. In an aspect, the processing logic 302 operates toperform these operations. The processing logic 302 operates to attemptto acquire flow data for registered flows in the selected FG plus otherregistered flows carried on the same RF channel.

At block 1106, a switch (if required) is performed to the RF carryingthe selected flow group. In an aspect, the processing logic 302 controlsthe channel switch logic 310 to switch to the RF channel carrying theselected FG. An RF switch will not be required if device current RF isthe RF carrying the selected FG.

At block 1108, at attempt is made to acquire appropriate set of the OISand control channel information on the new RF channel. In an aspect, theoverhead input logic 306 obtains the OIS and control channel informationfrom the new RF channel.

At block 1110, a determination is made as to whether the acquisition ofthe OIS and the control channel information succeeded. In an aspect, ifthe acquisition of the OIS and control channel information wassuccessful, the method proceeds to block 1112. If the acquisition of theOIS and control channel information was not successful, the methodproceeds to block 1114.

At block 1112, the execution of the DAP procedure continues to acquiredata associated with registered flows. In an aspect, the processinglogic 302 operates to continue executing the DAP procedure.

At block 1114, a handoff procedure for registered flows in selected FGis executed. For example, the handoff procedure described in FIG. 8 isexecuted to hand off to a new neighboring RF channel in an attempt toobtain data for the registered flows in the selected FG.

At block 1116, a determination is made as to whether the handoff wassuccessful. If the handoff was successful, the method proceeds to block1112. If the handoff was not successful, the method proceeds to block1118.

At block 1118, all the flow groups carried on the current RF channel areremoved from the DAP flow group list. In an aspect, the processing logic302 operates to remove FGs from the DAP flow group list.

At block 1120, a determination is made as to whether there are any moreflow groups left in the DAP flow group list. In an aspect, theprocessing logic 302 operates to make this determination. In an aspect,if there are more flow groups left in the DAP flow group list, themethod proceeds to block 1104. If there are no more flow groups left inthe DAP flow group list, the method proceeds to block 1122.

At block 1122, the DAP flow group list is reset to all computed flowgroups. In an aspect, the processing logic 302 operates to reset the DAPflow group list.

At block 1124, monitoring of OIS information is scheduled so thatacquisition for OIS, CC and flow data for FGs can be attempted againafter a selected time interval.

Thus, the method 1100 operates to provide a handoff event trigger forregistered flows for use in aspects of a handoff system. It should benoted that the method 1100 represents just one implementation and thatother implementations are possible within the scope of the aspects.

FIG. 12 shows a method 1200 for providing a handoff trigger event forregistered flows for use in aspects of a handoff system. In an aspect,the method 1200 initiates a handoff in the event of data acquisitionfailure with respect to registered flows. In an aspect, the processinglogic 302 executes one or more sets of codes to control the handofflogic 300 to perform the functions described below.

At block 1202, a device is currently decoding registered flowsassociated with a selected flow group on a current RF. The device alsodecodes registered flows associated with other FGs carried on thecurrent RF.

At block 1204, a determination is made to determine whether dataacquisition for all MLCs associated with registered flows in theSelected FG failed or OIS acquisition failed on the current RF. In anaspect, the processing logic 302 makes this determination. If there areno MLCs and OIS failures, the method proceeds to block 1202. If there iseither failure of all MLCs associated with registered flows in theSelected FG or the failure of OIS acquisition, then the method proceedsto block 1206.

At block 1206, a handoff procedure for the registered flows in theselected FG is executed. For example, the handoff procedure described inFIG. 8 is executed to hand off to a new neighboring RF channel tosuccessfully acquire OIS and registered flows in the selected FG.

At block 1208, a determination is made as to whether the handoff wassuccessful. In an aspect, the processing logic 302 makes thisdetermination. If the handoff was successful, the method proceeds toblock 1210. If the handoff was not successful, the method proceeds toblock 1212.

At block 1212, all the flow groups carried on the current RF channel areremoved from the DAP flow group list. In an aspect, the processing logic302 operates to remove FGs from the DAP flow group list.

At block 1214, a determination is made as to whether there are more flowgroups left in the DAP flow group list. In an aspect, the processinglogic 302 operates to make this determination. If there are more flowgroups left, the method proceeds to block 1216 to start executing a DAPprocedure. If there are no more flow groups left in the DAP flow grouplist, the method proceeds to block 1218.

At block 1216, a DAP procedure is executed to acquired data foradditional flow groups that are left in the DAP flow group list.

At block 1218, the DAP flow group list is reset to list all computedflow groups. In an aspect, the processing logic 302 operates to resetthe DAP flow group list.

At block 1220, monitoring of OIS information is scheduled so thatacquisition for OIS, CC and flow data for FGs can be attempted againafter a selected time interval.

Thus, the method 1200 operates to provide a handoff event trigger forregistered flows for use in aspects of a handoff system. It should benoted that the method 1200 represents just one implementation and thatother implementations are possible within the scope of the aspects.

FIG. 15 shows handoff logic 1500 for use in aspects of a handoff system.For example, the handoff logic 1500 is suitable for use as the handofflogic 300 shown in FIG. 3. In an aspect, the handoff logic 1500 isimplemented by at least one integrated circuit comprising one or moremodules configured to provide aspects of a handoff system as describedherein. For example, in an aspect, each module comprises hardware and/orhardware executing software.

The handoff logic 1500 comprises a first module comprising means (1502)for generating seamless handoff tables and partially seamless handofftables for multiplexes carried in a current LOI, wherein the seamlessand partially seamless handoff tables comprise neighboring RF channelscarrying one or more of the multiplexes in the current LOI, which in anaspect comprises the processing logic 302. The handoff logic 1500 alsocomprises a second module comprising means (1504) for detecting ahandoff event initiated by acquisition failures on a current RF, whichin an aspect comprises the processing logic 302. The handoff logic 1500also comprises a third module comprising means (1506) for selecting aselected RF channel from the seamless and partially seamless handofftables, which in an aspect comprises the processing logic 302. Thehandoff logic 1500 also comprises a fourth module comprising means(1508) for performing a handoff to the selected RF channel, which in anaspect comprises the channel switch logic 310.

Content Preserving Handoff

In an aspect, a content preserving handoff is provided wherein thehandoff system operates to hand off to a horizontal RF in a neighboringLOI carrying the same set or a superset of multiplexes as carried in acurrent LOI. After a content preserving handoff, content is preserved inthe sense that the content available in the old LOI is also available inthe new LOI. For example, a Wide+Local seamless handoff is a specialcase of a content preserving handoff where the LOI associated with a newRF carries at least same set of wide and local content multiplexes asthe old LOI. The content preserving handoff allows a device to move to aneighboring LOI which carries at least the same content as the currentLOI and provide better signal strength for RF channels carried in thenew LOI. This provides an overall improved success probability forcontent data acquisition in the multi-frequency network.

In an aspect, the handoff system performs a content preserving handoffif the following handoff conditions are met at the device:

-   1. Device has one or more flows registered from an upper layer over    one or more RFs.-   2. Device does not have any activated real time flows.-   3. Device is not actively decoding any registered flows (i.e., all    of the registered flows are not being broadcast currently).-   4. Device has at least one good RF (RF for which OIS acquisition was    successful)) in the current LOI.-   5. Device has at least one bad RF in the current LOI (RF for which    OIS acquisition failed) or has at least one good RF (RF for which    OIS acquisition was successful) with an RSSI that is below a    selected good RF threshold (Good_RF_Thresh).

In an aspect, the handoff system maintains a list of neighboring LOIswhich can provide a content preserving handoff. The content preserving(CP) LOIs are those LOIs which carry at least same set of content as thedevice's current LOI. In an aspect, the handoff system performs thecontent preserving handoff if the set of RFs carrying the same content(as current LOI) in a CP LOI have overall better signal strength thanRFs in the current LOI. In another aspect, the handoff system performsthe content preserving handoff only if the broadcast of any of theregistered flow data is not starting before a selected time windowduration from a current time. This ensures that if the registered flowdata broadcast is starting within the selected time window duration, itdoes not get interrupted by the content preserving handoff. If noappropriate CP neighboring LOI exists, the content preserving handoff isnot performed. By providing the content preserving handoff, the handoffsystem operates to provide the following features.

-   1. Increase in the success probability for overall flow data    acquisition for registered & active flows because RFs in the new LOI    have an overall better signal strength than RFs in the current LOI.-   2. If the current LOI has good RFs with RSSI below the    Good_RF_Thresh, a content preserving handoff may improve the    probability of successful data reception for these RFs.-   3. If the current LOI has bad RFs for which OIS acquisition failed,    a content preserving handoff may improve the probability of    successful data reception for these bad RFs.

FIG. 16 shows an exemplary content preserving handoff table 1600applicable for use in aspects of a handoff system. In an aspect, thecontent preserving handoff table 1600 is generated by the processinglogic 302. The content preserving handoff table contains data related toneighboring CP LOIs for the device's current LOI. The content preservinghandoff table 1600 comprises a LOI identifier 1602 which identifiesparticular CP LOIs for the device's current LOI in the multi-frequencynetwork. The content preserving handoff table 1600 also comprises a sumof weights identifier 1604 that indicates an overall weight valueassociated with RFs in a particular CP LOI identified by a LOIidentifier 1602. The content preserving handoff table 1600 alsocomprises a total number of multiplexes indicator 1606 that indicatesthe total number of wide and local multiplexes available in a particularCP LOI identified by a LOI identifier 1602. It should be noted that thetable 1600 is designed to include information associated with thecurrent LOI as well. The information associated with the current LOI isused to determine if a content preserving handoff should be performed.

In an aspect, the RFs carrying the same multiplex (as the current LOI)in the each CP LOI identified in the content preserving table 1600 areassigned weights as follows:

-   1. For a selected RF, if the RSSI>Good_RF_Thresh, the weight is set    equal to one, else the weight is set equal to zero;-   2. Weights are assigned separately for wide and local multiplexes.    Thus an RF with RSSI>Good_RF_Thresh in a CP LOI and which carries    the same wide and local content multiplexes as the current LOI is    assigned a weight equal to two (one for wide multiplex and one for    local multiplex).

The sum of weights identifier 1604 is computed for a particular CP LOIby adding together weights assigned to each RF which carries samecontent multiplexes (as current LOI) in the CP LOI.

The content preserving LOIs are assigned ranks based on informationincluded in the content preserving handoff table 1600. It should benoted that the device's current LOI also has an entry in the contentpreserving handoff table and is assigned a rank as other CP LOs. Thecontent preserving LOIs are examined in their rank order for performinga content preserving handoff. In an aspect, the handoff system assignsranks to CP LOIs and current LOI based on following criteria.

-   1. A LOI with a higher total sum of weights is assigned a higher    rank.-   2. Multiple LOIs with the same total weights are assigned ranks    based on the total number of wide and local multiplexes carried in    those LOs. A LOI carrying more total number of multiplexes is    assigned a higher rank.

In an aspect, the handoff system operates to determine a LOI to which acontent preserving handoff is performed based on the rank order of LOIsidentified in the table 1600. A content preserving handoff is performedif it is determined that a neighboring CP LOI has a higher rank than thecurrent LOI. The handoff system starts a content preserving handoffattempt with the neighboring CP LOI having the highest rank. The contentpreserving handoff is performed to the seamless RF in the selected CPLOI which is carrying same wide and/or local content multiplexes as thecurrent RF in the current LOI. It should be noted that depending on themultiplexes available in neighboring LOs, table 1600 may not include anyCP LOs. This will happen if no neighboring LOI carries same set of wideand local multiplexes as the current LOI. In this case, no contentpreserving handoff will be performed.

FIG. 17 shows an exemplary method 1700 for providing a contentpreserving handoff for use in aspects of a handoff system. In an aspect,the processing logic 302 executes one or more sets of codes to controlthe handoff logic 300 to perform the functions described below.

At block 1702, a determination is made as to whether selected contentpreserving handoff conditions have been met. In an aspect, the selectedcontent preserving handoff conditions are as described above. If thecontent preserving handoff conditions have been met, the method proceedsto block 1704. If not, the method ends.

At block 1704, the RFs associated with current and neighboring CP LOIsare monitored to determine their signal strength (i.e., RSSI) forinclusion in the content preserving handoff table 1600. The handoffsystem uses the signal strength values to compute information forcurrent and CP LOIs in the content preserving handoff table 1600. In anaspect, the processing logic 302 controls a receiver at the device toperform this function.

At block 1706, a LOI with the next highest rank is selected from thecontent preserving handoff table 1600. In an aspect, the processinglogic 302 performs this function.

At block 1708, a determination is made as to whether the selected LOI isdifferent than the current LOI. If the selected LOI is different fromthe current LOI, the method proceeds to block 1710. If the selected LOIis not different from the current LOI, the method proceeds to block1712.

At block 1710, a destination RF is set to an RF in the selected LOIcarrying at least the same wide content multiplex as the current RF. Ifan RF exists in the selected LOI which carries same wide and localcontent multiplexes as the current RF, the destination RF is set thatRF.

At block 1712, the content preserving handoff is not performed and themethod ends.

At block 1714, a switch to the destination RF is performed. In anaspect, the processing logic 302 controls a device receiver to performthis function.

At block 1716, a wide and local system acquisition procedure isperformed. Based on the results of the acquisition procedure, a path isselected from three paths beginning at blocks 1718, 1720, and 1722.

At block 1718, the acquisition of the WOIS has failed and the methodproceeds to block 1706.

At block 1720, the acquisition of the WOIS is successful and theacquisition of the LOIS has failed. The method then proceeds to block1724.

At block 1724, a determination is made as to whether a contentpreserving handoff type parameter is set to “wide.” A more detaileddescription of the handoff type parameter is provided below. If thehandoff type parameter is set to “wide” the method proceeds to block1726. If the handoff type parameter is not set to “wide” the methodproceeds to block 1706.

At block 1722, the acquisition of the WOIS and LOIS are successful andthe method proceeds to block 1726.

At block 1726, control channel data on the new RF channel is acquired.The method then ends.

Thus, the method 1700 operates to provide a content preserving handofffor use in aspects of a handoff system. It should be noted that themethod 1700 represents just one implementation and that otherimplementations are possible within the scope of the aspects.

CP Handoff Type Determination

In various aspects, a content preserving handoff type (CP_handoff_type)parameter is determined based on the type of registered flows at thedevice. In an aspect, the handoff system sets the CP_handoff_type to“wide” if only wide flows are currently registered from the upper layer.In another aspect, the handoff system sets the CP_handoff_type to“local” if only local flows are currently registered from the upperlayer. In still another aspect, the handoff system sets theCP_handoff_type to “wide+local” if both wide and local flows arecurrently registered flows from the upper layer.

FIG. 18 shows handoff logic 1800 for use in aspects of a handoff system.For example, the handoff logic 1800 is suitable for use as the handofflogic 300 shown in FIG. 3. In an aspect, the handoff logic 1800 isimplemented by at least one integrated circuit comprising one or moremodules configured to provide aspects of a handoff system as describedherein. For example, in an aspect, each module comprises hardware and/orhardware executing software.

The handoff logic 1800 comprises a first module comprising means (1802)for generating a content preserving handoff table, wherein the contentpreserving handoff table comprises a current local operationsinfrastructure (LOI) and neighboring LOIs carrying at least the samewide and local content multiplexes as the current LOI, which in anaspect comprises the processing logic 302. The handoff logic 1800 alsocomprises a second module comprising means (1804) for determining thathandoff conditions are met for a content preserving handoff, which in anaspect comprises the processing logic 302. The handoff logic 1800 alsocomprises a third module comprising means (1806) for selecting aselected LOI from the content preserving handoff table and a selected RFchannel associated with the selected LOI, which in an aspect comprisesthe processing logic 302. The handoff logic 1800 also comprises a fourthmodule comprising means (1808) for performing a handoff to the selectedRF channel in the selected LOI if the selected LOI is different than thecurrent LOI, which in an aspect comprises the channel switch logic 310.

Thus, the various illustrative logics, logical blocks, modules, andcircuits described in connection with the aspects disclosed herein maybe implemented or performed with a general purpose processor, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but, in the alternative, the processor may be any conventionalprocessor, controller, microcontroller, or state machine. A processormay also be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The steps of a method or algorithm described in connection with theaspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor, such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

The description of the disclosed aspects is provided to enable anyperson skilled in the art to make or use the present invention. Variousmodifications to these aspects may be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects, e.g., in an instant messaging service or any generalwireless data communication applications, without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the aspects shown herein but is to be accordedthe widest scope consistent with the principles and novel featuresdisclosed herein. The word “exemplary” is used exclusively herein tomean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects.

Accordingly, while aspects of a handoff system have been illustrated anddescribed herein, it will be appreciated that various changes can bemade to the aspects without departing from their spirit or essentialcharacteristics. Therefore, the disclosures and descriptions herein areintended to be illustrative, but not limiting, of the scope of theinvention, which is set forth in the following claims.

1. A method for RF channel handoff in a multi-frequency network, themethod comprising: generating a content preserving handoff table,wherein the content preserving handoff table comprises a current localoperations infrastructure (LOI) and neighboring LOIs carrying at leastthe same wide and local content multiplexes as the current LOI;determining that handoff conditions are met for a content preservinghandoff; selecting a selected LOI from the content preserving handofftable and a selected RF channel associated with the selected LOI; andperforming a handoff to the selected RF channel in the selected LOI ifthe selected LOI is different than the current LOI.
 2. The method ofclaim 1, wherein said determining comprises determining that the contentpreserving handoff conditions are met if: one or more flows areregistered; no real time flows are currently active; no registered flowsare being decoded currently; there is at least one good RF in thecurrent LOI; there is at least one bad RF in the current LOI or there isat least one good RF in the current LOI with signal strength below aselected good RF threshold; and broadcast of content for no registeredflows is to start before a selected time window from a current time. 3.The method of claim 1, wherein said selecting comprises: ranking thecurrent LOI and the neighboring LOIs based on RF signal strength andtotal number of multiplexes in each LOs; and selecting the selected LOIto be a LOI with the highest rank.
 4. The method of claim 1, whereinsaid selecting comprises selecting the selected RF channel to be an RFchannel in the selected LOI that carries at least the same widemultiplex as a current RF channel in the current LOI.
 5. The method ofclaim 1, wherein said selecting comprises selecting the selected RFchannel to be an RF channel in the selected LOI that carries the samewide and local content multiplexes as a current RF channel in thecurrent LOI.
 6. The method of claim 3, further comprising: performingfollowing operations once for each LOI with rank higher than the currentLOI in the content preserving handoff table until a successful contentpreserving handoff occurs: selecting the selected LOI to be a LOI withnext highest rank and a selected RF channel associated with the selectedLOI; and performing a handoff to the selected RF channel in the selectedLOI.
 7. The method of claim 3, wherein said ranking further comprises:assigning weight one to an RF channel if its signal strength is above aselected threshold; assigning weight zero to the RF channel if itssignal strength is not above a selected threshold; determining a ‘sum ofweights’ for a LOI by adding together weights assigned to RF channels inthat LOI which carry the same content multiplexes as the current LOI;assigning a higher rank to a LOI which has higher sum of weights; andassigning a higher rank to a LOI with a higher total number of wide andlocal content multiplexes among LOIs with a same ‘sum of weights’
 8. Themethod of claim 7, further comprising assigning separate weights to anRF channel for wide and local content multiplexes, respectively.
 9. Anapparatus for RF channel handoff in a multi-frequency network, theapparatus comprising: processing logic configured to: generate a contentpreserving handoff table, wherein the content preserving handoff tablecomprises a current local operations infrastructure (LOI) andneighboring LOIs carrying at least the same wide and local contentmultiplexes as the current LOI; determine that handoff conditions aremet for a content preserving handoff; and select a selected LOI from thecontent preserving handoff table and a selected RF channel associatedwith the selected LOI; and channel switch logic configured to perform ahandoff to the selected RF channel in the selected LOI if the selectedLOI is different than the current LOI.
 10. The apparatus of claim 9,wherein said processing logic is configured to determine that thecontent preserving handoff conditions are met if: one or more flows areregistered; no real time flows are currently active; no registered flowsare being decoded currently; there is at least one good RF in thecurrent LOI; there is at least one bad RF in the current LOI or there isat least one good RF in the current LOI with signal strength below aselected good RF threshold; and broadcast of content for no registeredflows is to start before a selected time window from a current time. 11.The apparatus of claim 9, wherein said processing logic is configuredto: rank the current LOI and the neighboring LOIs based on RF signalstrength and total number of multiplexes in each LOs; and select theselected LOI to be a LOI with the highest rank.
 12. The apparatus ofclaim 9, wherein said processing logic is configured to select theselected RF channel to be an RF channel in the selected LOI that carriesat least the same wide multiplex as a current RF channel in the currentLOI.
 13. The apparatus of claim 11, wherein said processing logic isconfigured to: perform following operations once for each LOI with rankhigher than the current LOI in the content preserving handoff tableuntil a successful content preserving handoff occurs: select theselected LOI to be a LOI with next highest rank and a selected RFchannel associated with the selected LOI; and perform a handoff to theselected RF channel in the selected LOI.
 14. The apparatus of claim 11,wherein said processing logic is configured to: assign weight one to anRF channel if its signal strength is above a selected threshold; assignweight zero to the RF channel if its signal strength is not above aselected threshold; determine a ‘sum of weights’ for a LOI by addingtogether weights assigned to RF channels in that LOI which carry thesame content multiplexes as the current LOI; assign a higher rank to aLOI which has higher sum of weights; and assign a higher rank to a LOIwith a higher total number of wide and local content multiplexes amongLOIs with a same ‘sum of weights’
 15. An apparatus for RF channelhandoff in a multi-frequency network, the apparatus comprising: meansfor generating a content preserving handoff table, wherein the contentpreserving handoff table comprises a current local operationsinfrastructure (LOI) and neighboring LOIs carrying at least the samewide and local content multiplexes as the current LOI; means fordetermining that handoff conditions are met for a content preservinghandoff; means for selecting a selected LOI from the content preservinghandoff table and a selected RF channel associated with the selectedLOI; and means for performing a handoff to the selected RF channel inthe selected LOI if the selected LOI is different than the current LOI.16. The apparatus of claim 15, wherein said means for determiningcomprises means for determining that the content preserving handoffconditions are met if: one or more flows are registered; no real timeflows are currently active; no registered flows are being decodedcurrently; there is at least one good RF in the current LOI; there is atleast one bad RF in the current LOI or there is at least one good RF inthe current LOI with signal strength below a selected good RF threshold;and broadcast of content for no registered flows is to start before aselected time window from a current time.
 17. The apparatus of claim 15,wherein said means for selecting comprises: means for ranking thecurrent LOI and the neighboring LOIs based on RF signal strength andtotal number of multiplexes in each LOs; and means for selecting theselected LOI to be a LOI with the highest rank.
 18. The apparatus ofclaim 15, wherein said means for selecting comprises means for selectingthe selected RF channel to be an RF channel in the selected LOI thatcarries at least the same wide multiplex as a current RF channel in thecurrent LOI.
 19. The apparatus of claim 17, further comprising: meansfor performing following operations once for each LOI with rank higherthan the current LOI in the content preserving handoff table until asuccessful content preserving handoff occurs: selecting the selected LOIto be a LOI with next highest rank and a selected RF channel associatedwith the selected LOI; and performing a handoff to the selected RFchannel in the selected LOI.
 20. The method of claim 17, wherein saidmeans for ranking further comprises: means for assigning weight one toan RF channel if its signal strength is above a selected threshold;means for assigning weight zero to the RF channel if its signal strengthis not above a selected threshold; means for determining a ‘sum ofweights’ for a LOI by adding together weights assigned to RF channels inthat LOI which carry the same content multiplexes as the current LOI;means for assigning a higher rank to a LOI which has higher sum ofweights; and means for assigning a higher rank to a LOI with a highertotal number of wide and local content multiplexes among LOIs with asame ‘sum of weights’
 21. A computer program product for RF channelhandoff in a multi-frequency network, the computer program productcomprising: a machine-readable medium comprising: a first set of codesfor causing a computer to generate a content preserving handoff table,wherein the content preserving handoff table comprises a current localoperations infrastructure (LOI) and neighboring LOIs carrying at leastthe same wide and local content multiplexes as the current LOI; a secondset of codes for causing a computer to determine that handoff conditionsare met for a content preserving handoff; a third set of codes forcausing a computer to select a selected LOI from the content preservinghandoff table and a selected RF channel associated with the selectedLOI; and a fourth set of codes for causing a computer to perform ahandoff to the selected RF channel in the selected LOI if the selectedLOI is different than the current LOI.
 22. The machine-readable mediumof claim 21, wherein said second set of codes are configured to causethe computer to determine that the content preserving handoff conditionsare met if: one or more flows are registered; no real time flows arecurrently active; no registered flows are being decoded currently; thereis at least one good RF in the current LOI; there is at least one bad RFin the current LOI or there is at least one good RF in the current LOIwith signal strength below a selected good RF threshold; and broadcastof content for no registered flows is to start before a selected timewindow from a current time.
 23. The machine-readable medium of claim 21,wherein said third set of codes further comprise: a fifth set of codesfor causing the computer to rank the current LOI and the neighboringLOIs based on RF signal strength and total number of multiplexes in eachLOs; and a sixth set of codes for causing the computer to select theselected LOI to be a LOI with the highest rank.
 24. The machine-readablemedium of claim 21, wherein said third set of codes are configured tocause the computer to select the selected RF channel to be an RF channelin the selected LOI that carries at least the same wide multiplex as acurrent RF channel in the current LOI.
 25. The machine-readable mediumof claim 23, further comprising: a seventh set of codes configured tocause the computer to perform following operations once for each LOIwith rank higher than the current LOI in the content preserving handofftable until a successful content preserving handoff occurs: select theselected LOI to be a LOI with next highest rank and a selected RFchannel associated with the selected LOI; and perform a handoff to theselected RF channel in the selected LOI.
 26. The machine-readable mediumof claim 23, wherein said fifth set of codes are configured to cause thecomputer to: assign weight one to an RF channel if its signal strengthis above a selected threshold; assign weight zero to the RF channel ifits signal strength is not above a selected threshold; determine a ‘sumof weights’ for a LOI by adding together weights assigned to RF channelsin that LOI which carry the same content multiplexes as the current LOI;assign a higher rank to a LOI which has higher sum of weights; andassign a higher rank to a LOI with a higher total number of wide andlocal content multiplexes among LOIs with a same ‘sum of weights’
 27. Atleast one integrated circuit configured for RF channel handoff in amulti-frequency network, the at least one integrated circuit comprising:a first module configured to generate a content preserving handofftable, wherein the content preserving handoff table comprises a currentlocal operations infrastructure (LOI) and neighboring LOIs carrying atleast the same wide and local content multiplexes as the current LOI; asecond module configured to determine that handoff conditions are metfor a content preserving handoff; a third module configured to select aselected LOI from the content preserving handoff table and a selected RFchannel associated with the selected LOI; and a fourth module configuredto perform a handoff to the selected RF channel in the selected LOI ifthe selected LOI is different than the current LOI.
 28. The at least oneintegrated circuit of claim 27, wherein said second module is configuredto determine that the content preserving handoff conditions are met if:one or more flows are registered; no real time flows are currentlyactive; no registered flows are being decoded currently; there is atleast one good RF in the current LOI; there is at least one bad RF inthe current LOI or there is at least one good RF in the current LOI withsignal strength below a selected good RF threshold; and broadcast ofcontent for no registered flows is to start before a selected timewindow from a current time.
 29. The at least one integrated circuit ofclaim 27, further comprising: a fifth module configured to rank thecurrent LOI and the neighboring LOIs based on RF signal strength andtotal number of multiplexes in each LOs; and a sixth module configuredto select the selected LOI to be a LOI with the highest rank.
 30. The atleast one integrated circuit of claim 27, wherein said third module isconfigured to select the selected RF channel to be an RF channel in theselected LOI that carries at least the same wide multiplex as a currentRF channel in the current LOI.
 31. The at least one integrated circuitof claim 29, further comprising: a seventh module configured to performfollowing operations once for each LOI with rank higher than the currentLOI in the content preserving handoff table until a successful contentpreserving handoff occurs: select the selected LOI to be a LOI with nexthighest rank and a selected RF channel associated with the selected LOI;and perform a handoff to the selected RF channel in the selected LOI.32. The at least one integrated circuit of claim 29, wherein said fifthmodule is configured to: assign weight one to an RF channel if itssignal strength is above a selected threshold; assign weight zero to theRF channel if its signal strength is not above a selected threshold;determine a ‘sum of weights’ for a LOI by adding together weightsassigned to RF channels in that LOI which carry the same contentmultiplexes as the current LOI; assign a higher rank to a LOI which hashigher sum of weights; and assign a higher rank to a LOI with a highertotal number of wide and local content multiplexes among LOIs with asame ‘sum of weights’